PSVII-7 - Genetic evaluation of feed and water intake behavior traits in feedlot cattle

Abstract: Feed and water intake are two economically relevant traits of cattle production. These traits can impact producer profitability and efficiency. Feed intake and, to a lesser degree, water intake have been studied previously. However, there is limited research on the animal behaviors associated with intake and the literature lacks standardized phenotypes for these behaviors. The objective of this study was to estimate heritabilities and variance components for feed and water intake behavior traits in feedlot steers. An Insentec system (Hokofarm Group, The Netherlands) was used to obtain feed (n=824) and water (n=786) intakes from crossbred steers for 70 days. Daily dry matter intake (DMI) and daily water intake (DWI) records were used to compute five behaviors for both feed and water intake: number of sessions (NS), intake rate (IR), session size (SS), time per session (TS), and session interval (SI). A mixed linear model was fit for all traits to estimate variance components and heritabilities with a base model including the fixed effects group(pen) and breed composition and the random effect animal. Additional covariates were tested and added to the base model if improved model fit. Heritabilities for feed intake behaviors were 0.50 ± 0.12, 0.63 ± 0.12, 0.40 ± 0.13, 0.35 ± 0.12, and 0.60 ± 0.12 for NS, IR, SS, TS, and SI, respectively. Heritabilities for water intake behaviors were 0.56 ±0.11, 0.88 ± 0.07, 0.70 ± 0.11, 0.54 ± 0.12, and 0.80 ± 0.10 for NS, IR, SS, TS, and SI, respectively. Dry matter intake and DWI had heritabilities of 0.57 ± 0.11 and 0.44 ± 0.11, respectively. Bivariate models including feed intake behaviors and DMI as well as bivariate models including water intake behaviors and DWI were used to obtain correlations between intake and intake behaviors. Phenotypic correlations varied widely between pairs of traits for both feed and water intake behaviors (-0.83 to 0.82). Genetic correlations between DMI and feed intake behaviors were moderate to high (-0.64 ± 0.34 to 0.49 ± 0.16), while genetic correlations between DWI and water intake behaviors were low to moderate (-0.37 ± 0.14 to 0.48 ± 0.15). Significant (‑log₁₀ p-value ≥ 4.5) SNPs were identified for the feed and water intake behaviors. The number of significant SNPs identified for feed intake traits, NS, IR, SS, TS, SI, and DMI were 3, 10, 8, 8, 5, and 5, respectively. The number of significant SNPs identified for water intake traits, NS, IR, SS, TS, SI, and DWI were 4, 8, 3, 2, 5, and 4, respectively. Candidate genes and previously reported quantitative trait loci near significant SNPs were identified. The results indicated that feed and water intake behaviors are heritable and may be one additional route to evaluating feed and water intake.